Boehm 1996.

Methods	2‐arm RCT with individual randomisation (a 2nd non‐randomised control group have not been included in the analysis).
Participants	Setting: 42 women at high risk of preterm birth attending 2 hospitals in the USA between 1989 to 1993; recruitment from 20 weeks’ gestation.  Inclusion criteria: 18 years or more, previous preterm birth (< 37 weeks and not related to incompetent cervix, multiple gestation, pregnancy‐induced hypertension or intrauterine growth retardation), 20 weeks' gestation or more and absence of maternal conditions that might lead to early delivery (e.g. diabetes or drug abuse), telephone access at home.
Interventions	Intervention group (21 women) in addition to usual care, daily telephone calls from recruitment to delivery from the research nurse, women were asked about symptoms and opportunity for women to discuss any concerns. Control group (21 women) usual care which included 24 hour phone access help line if they had any problems and prenatal visits at least fortnightly from 20 weeks to delivery.
Outcomes	Diagnosis and treatment of preterm labour, number of prenatal visits, mode of delivery, mean length of hospital stay for mother and baby, gestational age at delivery and infant birthweight.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not described.
Allocation concealment (selection bias)	Unclear risk	Not described.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not blinded.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Not blinded.
Incomplete outcome data (attrition bias) All outcomes	Low risk	It appeared that all women randomised were followed up.
Selective reporting (reporting bias)	Unclear risk	Assessment from published study report.
Other bias	Unclear risk	Groups appeared comparable at baseline.